livestock and pets despawning

We are having issues with animals despawning while in pens, we had 2 adult cows, 2 baby cows, a white, gray and black sheep, as well as a pig. Came back not 10 mins later, only the two sheep and baby cows were there. I have Axo's in a pond in my house, every day i put some in there, the most i have had is 5..every day i come in to either none or just 1. Even animals with name tags are disappearing. Its very frustrating.